Kinetic and mechanistic study of the reduction of 2,6-dichlorophenol indophenol by dithionites

✍ Scribed by C.N Konidari; M.I. Karayannis

• Book ID: 104100781
• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 666 KB
• Volume: 224
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/s0003-2670(00)86559-9

✦ Synopsis

The reaction of 2,6-dichlorophenolindophenol (DCPI) and dithionites is studied kinetically by applying the stopped-flow technique. Reaction rate constants are given for the pH range 1.30-6.80. The reaction was found to follow first-order kinetics with respect to each of the reactants. For pH 3.97,5.10 and 6.80, the second-order reaction rate constant was determined by applying four different techniques. Mean values of k= 172 f 5,200 + 2 and 276 + 4 1 mol-' s-i are given for pH 3.97, 5.10 and 6.80, respectively. A mechanism is proposed for the reaction, which suggests partial reactions of all possible species of DCPI and dithionites at any pH. An equation for the calculation of k at any pH is derived, which gives k as a function of [H+ 1, the partial reaction rate constants and the dissociation constants of DCPI and H,S,O,. Values of reaction rate constants of all possible partial reactions are also presented.